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Autologous Blood Injections for Injured Tendons - The new Cortisone?
Autologous (one’s own) Blood Injections (ABI) are becoming increasingly common to facilitate tissue repair when injuries are slow to heal.

They are most widely used to treat painful tendons that have not responded fully to conservative measures such as rest, icing, bracing / taping, physiotherapy exercises, biomechanical correction, medications and steroid injections.  The most commonly treated tendons are the Achilles in the lower leg, the patella tendon in the front of the knee, the plantar fascia under the heel, and the dreaded Tennis Elbow (usually involving the Extensor Carpi Radialis Brevis tendon at the outer part of the elbow).   More recently ABI is also being used effectively to treat mild to moderate osteoarthritis in knee joints.

Tendinitis or Tendinosis?
Normally when we injure a structure, such as muscle, tendon, ligament or even cut our skin, damage to tiny blood vessels occurs, releasing blood and fluid into the area.  The resultant swelling, pain and stiffness we know as inflammation also brings cells to the area that eat up the damaged tissue and start regenerating new tissue.  With tendon pain that has been present for more than a few weeks though, studies have shown an absence of inflammatory cells and fluid, and instead a proliferation of fibroblast cells, new blood vessels and weak, disorganised scar tissue that takes up the space where the healthy tendon once was.  The term “Tendinosis” is replacing “Tendinitis” as it is now generally accepted that persistent tendon pain is no longer an inflammatory condition, but rather a degenerative problem from overuse or aging where the body fails to properly heal the tendon.

How does ABI work?
3-5ml of blood is withdrawn from the arm, the same way as for a blood test, and then injected with some local anaesthetic under ultrasound guidance into the affected tendon.  This contains small granular cells called platelets that release important growth factors (in particular Platelet-Derived Growth Factor) that switches on stem cells in the particular tissue to generate new tissue to heal the injured area.  For example if an Achilles tendon is painful, thickened and not responding to rehabilitation, a blood injection containing your own PDGF will activate the tendon cells (tenocytes and fibroblasts) to synthesise new collagen bundles to strengthen the tendon.  

Follow up and alternatives
Initial improvement may be seen within a few weeks, gradually increasing as the healing progresses.  Usually rehabilitation can start approximately 2 weeks post injection, and there is good evidence for the effectiveness of eccentric strengthening exercises (lengthening contractions like lowering a weight).  These are best guided by a physiotherapist.  Both ultrasound and MRI images have shown definitive tissue repair after ABI therapy, confirming the healing process, although sometimes a second injection may be required.  By contrast, the powerful steroidal anti-inflammatory drug Cortisone does not assist tendon healing but may assist with the pain associated with the injury.  A few studies have shown better effects after the first few months from ABI compared to cortisone for tennis elbow, but larger, longer-term studies are required.  Platelet Rich Plasma (PRP) injections use a centrifuge to separate and concentrate the platelets (8-10 times greater concentration) before re-injecting into the tendon, but again the research is yet to conclusively prove greater effectiveness that ABI alone.  Surgically debriding the tendon with a scalpel to create bleeding and reignite the healing cascade is less commonly performed, and is obviously more costly and invasive with greater risk of infection.  Speak to your doctor or physio about the best options for you. 

Peter Biskup
APA Titled Musculoskeletal Physiotherapist 

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